Method and apparatus for determining the location of a node in a wireless system

• US 20060239202A1
• Filed: 04/25/2005
• Published: 10/26/2006
• Est. Priority Date: 04/25/2005
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Shi, Qicai, Kyperountas, Spyros, Correal, Neiyer S., Niu, Feng
• Granted Patent: US 7,548,517 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 17/391 Modelling the propagation channel
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A location technique is utilized where channel-model parameters are originally estimated prior to location taking place. Location then takes place using a first set of known-located nodes, and the channel-model parameters are updated based on the distances resulting from the location estimate. Once the channel-model parameters have been updated, location again takes place using a second set of known-located nodes, node distances are calculated based on the produced locations and the channel-model parameters are again updated. This process continues until no significant change is observed between the previous and the newly estimated location, or until a maximum number of iterations is reached.

Claims

1. A method for determining a node'"'"'s location within a communication system, the method comprising the steps of:

(a) determining a plurality of distances to nodes within the communication system based on first channel-model parameters;

(b) producing a first location of the node based on the first set of distances;

(c) calculating new channel-model parameters based on the nodes location;

(d) recalculating the plurality of distances to nodes within the communication system based on the second channel-model parameters; and

(e) producing a second location of the node based on the recalculated distances.

2. The method of claim 1 further comprising the step of:

(f) determining if the second location converges.

3. The method of claim 2 further comprising the step of:

(g) re-performing steps (c)-(e) if the second location does not converge.

4. The method of claim 1 wherein the step of determining first and second channel-model parameters comprises the step of determining channel model parameters from a channel model relating path loss to separation distance.

5. The method of claim 1 wherein the step of determining the plurality of distances comprises the steps of:

determining a plurality of received signal strengths;

determining a plurality of path losses based on the plurality of received signal strengths; and

determining the plurality of distances to nodes within the communication system based on the plurality of path losses.

6. The method of claim 5 wherein the step of determining the plurality of path losses based on the plurality of received signal strengths comprises the steps of:

translating the plurality of received signal strengths to a plurality of received powers; and

translating the plurality of received powers to a plurality of path loss measurements.

7. The method of claim 1 further comprising the step of transmitting the second location.

8. A node comprising:

a receiver receiving transmissions from a plurality of nodes;

logic circuitry determining a plurality of distances to nodes within the communication system based on first channel-model parameters and received signal strengths of the transmissions, the logic circuitry additionally producing a first location of the node based on the plurality of distances, updating the channel-model parameters based on the nodes location, determining a second plurality of distances to nodes within the communication system based on the second channel-model parameters, and producing a second location of the node based on the second plurality of distances.

9. The apparatus of claim 8 wherein the logic circuitry determines if the second location converges.

10. The apparatus of claim 9 wherein the logic unit produces a third location if the second location does not converge.

11. The method of claim 8 wherein first and second channel-model parameters are channel model parameters from a channel model relating path loss to separation distance.

12. The apparatus of claim 8 further comprising a transmitter transmitting location estimates.